Currently, in the process industry of power plants, chemical plants, natural gas storage tanks, and the like, high temperature structures such as boilers, pipes, and the like are important elements, but the method for safe management of facilities determines the disorder of the facilities only by using interior and exterior image data through CCTVs and measuring the interior pressure and temperature of a structure, but does not precisely measure the displacement generated during the operation of the high temperature structure. Therefore, there is no means for preventing the damage of the facilities caused by stress concentration generated when the displacement during the operation exceeds the design value.
Especially, pipes widely used among the industrial facilities are inevitably necessary facilities for transferring the vapor generated in industrial boilers to power sources such as turbines. However, since the pipes various lengths and installation shapes, they generate various three dimensional displacements, according to the positions thereof, when operated.
The disorder of the pipes is determined by using support devices such as hangers, and measuring total unit displacements only in the vertical direction during the stop and the operation thereof in off line.
However, since many hangers are installed in each pipe, when a restriction is generated at one position of the pipe, the vertical displacements of adjacent hangers are generated as normal, but the horizontal displacements exceed the design values and cause various forms of damage. Thus, it is necessary to precisely measure the three-axial displacements generated during the operation of the structure.
In addition, in a case in which the structure, such as a pipe which is to be constantly measured, is installed at a position where it is dangerous to measure the structure, since operator is exposed to danger whenever measuring the structure, the measured data are not reliable. Further, although the life management and safety examination for the structure, such as a pipe and the like, is inevitably necessary, the three-axial displacement of the structure cannot be continuously measured and expensive equipment must be used.
The displacement measuring systems which have been used until now mainly measure one-dimensional displacement, and devices employing linear variable differential transformers (LVDT) of high cost, as well as lasers have been developed, but since three apparatuses should be attached at one position in order to measure the three-axial displacements, and since the apparatuses must be installed at various positions, considerable expenses are accrued when trying to measure the displacement of an entire facility.
Especially, since the installation shapes and positions of the pipes widely used among the industrial facilities are complex and the surrounding space is therefore small, measuring apparatuses of linear type are difficult to install for measuring three-axial displacement. Further, according to the conventional LVDT or the laser method, the direct engagement of a measuring apparatus and a high temperature structure is difficult to carry out due to the high surface temperature of the structure and separate heat radiating devices are needed.